Show "location" of Sun and Moon, Phase of Moon

[wbreeze]

By location, I mean, have a sun position indicator cross noon when the sun is crossing the meridian for current longitude, midnight when it is crossing the opposite meridian. The location on the dial shows what meridian it's over, relative to the current longitude. Is that clear? Make it clear.

Do the same for the moon, with a moon position indicator that changes phase - eight phases is good enough - full, new, waxing and waning quarter, gibeous, crescent.

This is in order to provide a rough indication of the phase of the tide. One starting resource is this one from John Walker who had fun in the eighties on a Sun workstation.

[wbreeze]

I think the correct term is “local hour angle” where zero is shown at the noon position on the dial and 180 at the midnight position.

[wbreeze]

For the sun, there is:

• A 2008 paper with fast algorithm promised by [1], copy requested from the authors. This is the "SG" algorithm surveyed in [3]
• A U.S. Government funded research report detailing implementation in [2]. This is the gold standard referenced in [3]
• A survey and fast and accurate enough algorithm [3] for less precise applications such as this one is open access, but the computational accuracy is only determined until 2030. It explains how to go about making approximations from [2].
• An article from SUNY, Albany [4] with an algorithm accurate for the century from 1950 to 2050. This is the "MICH" algorithm surveyed in [3]

[1] Grena, Roberto. (2008). An algorithm for the computation of the solar position. Solar Energy. 82. 462-470. 10.1016/j.solener.2007.10.001. https://www.sciencedirect.com/science/article/pii/S0038092X07002162 [2] NREL/TP-560-34302 retrieved as https://www.nrel.gov/docs/fy08osti/34302.pdf [3] Blanc, Philippe and Lucien Wald. “The SG2 algorithm for a fast and accurate computation of the position of the Sun for multi-decadal time period.” Solar Energy 86 (2012): 3072-3083. Retrieved from https://www.semanticscholar.org/paper/The-SG2-algorithm-for-a-fast-and-accurate-of-the-of-Blanc-Wald/6a9e1b97697e5b42fa3b13e6faba77ddb53c4cea [4] Michalsky, Joseph. (1988). The Astronomical Almanac's algorithm for approximate solar position (1950–2050). Solar Energy. 40. 227-235. 10.1016/0038-092X(88)90045-X retrieved from https://www.researchgate.net/publication/222131147_The_Astronomical_Almanac%27s_algorithm_for_approximate_solar_position_1950-2050

[wbreeze]

For the moon

• Chapront-Touze, M. & Chapront, J. (1983) “The lunar ephemeris ELP 2000” Astronomy and Astrophysics, Vol. 124, p. 50 (1983) https://ui.adsabs.harvard.edu/abs/1983A%26A...124...50C/abstract
• Chapront, J. & Francou, G.. (2003). The lunar theory ELP2000 revisited. Describes ELP/MPP02 https://www.researchgate.net/publication/252803329_The_lunar_theory_ELP2000_revisited. Files available from ftp://cyrano-se.obspm.fr/pub/2_lunar_solutions/2_elpmpp02/
• C++ implementation of ELP/MPP02 https://github.com/ytliu0/ElpMpp02
• This formula from Paul Schlyter in Stockholm, Sweden looks accurate enough, although it is a recursive procedure that needs to converge. https://www.stjarnhimlen.se/comp/ppcomp.html#6
• Standish, Myles & Williams, James. (2006). Orbital Ephemerides of the Sun, Moon, and Planets.
• NASA JPL Ephemerides https://ssd.jpl.nasa.gov/?ephemerides and SPICE Toolkit https://naif.jpl.nasa.gov/naif/toolkit.html
• Code sources from 2018 MIT press celestial calculations book by J.L. Laurence https://celestialcalculations.github.io/

[wbreeze]

Version tagged v1.1.0 displays both sun and moon hour angle. Merged without a PR (my bad). That wraps up this enhancement.